Positioning system, information supply device, terminal device, control method of information supply device, control program of information supply device, and computer readable recording medium recording control program of information supply device

ABSTRACT

A positioning system, wherein the communication base station has: signal transmitting means for transmitting a base station timing signal and a communication signal; the terminal has: standard timing signal correcting means; total delay information generating means for generating total delay information; and basic information transmitting means for transmitting basic information including the current position information and the total delay information to the information supply device and the like; and the information supply device has: base station position information storage means; basic information receiving means for receiving the basic; distance information generating means for generating distance information indicating a distance between a current position of the terminal and a position of the communication base station; 
     propagation delay information generating means for generating propagation delay; device peculiar delay information generating means for generating device peculiar delay information indicating a delay other than the propagation delay time; and the like.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/411,021, which claims priority to of Japanese PatentApplication No. 2005-129080 filed on Apr. 27, 2005. The entiredisclosure of the U.S. patent application Ser. No. 11/411,021 andJapanese Patent Application No. 2005-129080 is incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention relates to a positioning system which uses signalsfrom positioning satellites, information supply device, a terminal, acontrol method of the information supply device, a control program ofthe information supply device, and a computer readable recording mediumrecording the control program of the information supply device.

2. Related Art

In the past, for example, in a so-called digital mobile communicationsystem in a CDMA (Code Division Multiple Access) system, a method todetect a position based on an arrival time difference of a receivingsignal between a plurality of base stations and a mobile wirelessterminal relying on the assumption that a clock synchronization isassured among the plural base stations has been known (for example,JPA-7-181242).

In such a positioning method, there is a need for time (transmissiontiming) when a signal is transmitted from a base station to be precise.However, a timing when a signal is transmitted from a base station, isdelayed inside the base station between a time when a timing signal isgenerated and a time when the timing signal is transmitted, for example.

To the above mentioned situation, there is proposed a technique ofinstalling an offset measuring instrument, obtaining offset estimationvalues of a transmission timing based on signals received at a pluralityof monitoring points, and selecting the smallest value from among theseoffset estimation values to define an offset measurement value of thetransmission timing of a wireless base station (JP A-2002-217824, FIG.5, etc.).

However, inside the offset measuring instrument as well as inside thebase station, there occurs a signal delay such as an antenna delay, acable delay, or a filter delay. On the other hand, it is a generalportable terminal to carry out positioning based on signals from basestations, and a signal delay inside the portable terminal is not alwaysequal to that of the above-described offset measuring instrument.

Thus, if such a general portable terminal carries out positioning byusing the offset measurement value generated by the offset measuringinstrument, an error of positioning computation may be increased.

SUMMARY

Therefore, it is an advantage of some aspects of the invention toprovide a positioning system, an information supply device, a terminal,an information supply device control method, an information supplydevice control program, and a computer readable recording medium havingrecorded therein the information supply device control program, whichare capable of providing a correction value of a transmission timing ofa signal from a communication base station which is capable of reducingan error of positioning computation by a positioning terminal without aneed for a significant system change of the communication base station.

According to a first aspect of the invention, the advantage can beattained by a positioning system, comprising: a communication basestation; a terminal communicable with the communication base station; aninformation supply device communicable with the communication basestation and the terminal; wherein the communication base station has:signal transmitting means for transmitting a base station timing signaland a communication signal which the communication base stationgenerates; the terminal has: current position information generatingmeans for generating current position information indicating a currentposition based on satellite signals which are signals from positioningsatellites; satellite time information generating means for generatingsatellite time information indicating a satellite time which is a timeof the positioning satellites, based on the satellite signals; standardtiming signal correcting means for correcting a standard timing signalbased on the satellite time information; total delay informationgenerating means for generating total delay information indicating atotal delay which is a timing difference between the base station timingsignal and the standard timing signal; and basic informationtransmitting means for transmitting basic information including thecurrent position information and the total delay information to theinformation supply device; and the information supply device has: basestation position information storage means for storing base stationposition information indicating a position of the communication basestation; basic information receiving means for receiving the basicinformation from the terminal via the communication base station;distance information generating means for generating distanceinformation indicating a distance between a current position of theterminal and a position of the communication base station based on thecurrent position information and the base station position information;propagation delay information generating means for generatingpropagation delay information indicating a propagation delay timerequired for the communication signal to propagate the distance; devicepeculiar delay information generating means for generating devicepeculiar delay information indicating a delay other than the propagationdelay time based on the total delay information and the propagationdelay information; and device peculiar delay information transmittingmeans for transmitting the device peculiar delay information to apositioning terminal for carrying out positioning based on thecommunication signal from the communication base station, thepositioning terminal having configuration identical to the terminal withrespect to reception of the base station timing signal and thecommunication signal.

According to the configuration of the first aspect of the invention, thecommunication base station has signal transmitting means fortransmitting a base station timing signal and a communication signalwhich the communication base station generates.

It is general that the communication base station transmits the timingsignal and the communication signal, and thus, the communication basestation does not need a significant system change of a generalcommunication base station.

The terminal can generate the total delay information by the total delayinformation generating means. The total delay is a timing differencebetween the base station timing signal and the standard timing signalcorrected based on the satellite time information. The total delayincludes: a delay due to a drift when the base station timing signal isgenerated in the communication base station and a delay in thecommunication base station from generation to transmission of the basestation timing signal in the communication base station.

In addition, the total delay includes a propagation delay time requiredfor the base station timing signal to arrive from the communication basestation at the terminal.

Further, the total delay includes a delay inside the terminal caused bythe base station timing signal passing through a cable and a filter orthe like after arrival at an antenna of the terminal.

Furthermore, the total delay includes a delay of the standard timingsignal itself. The standard timing signal is corrected by the satellitetime information, and however, the satellite signal itself delays insidethe terminal. As a result, a delay occurs with the standard timingsignal as well, compared with a timing caused by the true satellitetime.

As described above, the total delay includes all of the delay inside thecommunication base station, the propagation delay between thecommunication base station and the terminal, and the delay insideterminal. For the purpose of computation of the total delay, there is noneed for computing individual delays such as a delay due to a drift or acable inside the communication base station, and there is no need forcomputing individual delays inside the terminal. Thus, it is possible toeliminate an effect of an error in computation of individual delaysinside the communication base station and inside the terminal and aneffect of an error in computation of propagation delay. That is, thetotal delay eliminates the effects of errors in delay computation due tothe individual causes described above while including all of the delaysinside the communication base station, inside the terminal, and betweenthe communication base station and the terminal.

On the other hand, the information supply device can receive the basicinformation from the terminal by the basic information receiving means.

The information supply device can generate distance informationindicating a distance between a current position of the terminal and aposition of the communication base station by the distance informationgenerating means.

The information supply device can generate propagation delay informationindicating a time required for the communication signal to propagate thedistance by the propagation delay information generating means.

The information supply device can generate device peculiar delayinformation indicating a delay other than the propagation delay time bythe device peculiar delay information generating means.

The above described device peculiar delay information is a delay otherthan the propagation delay time, and thus, is information indicating adelay inside the communication base station and the terminal. Asdescribed above, the total delay is computed eliminating individualdelay computation errors inside the communication base station and theterminal. In addition, the communication signal propagates at an lightspeed, and thus, the information supply device can compute thepropagation delay time precisely.

As described above, the total delay eliminates an effect of an error indelay computation due to the individual causes described above whileincluding all the delays inside the communication base station, insidethe terminal, and between the communication base station and theterminal.

In addition, the information supply device can compute the propagationdelay time precisely. Thus, the information supply device can generatethe device peculiar delay information while eliminating an effect of anerror in delay computation due to the individual causes inside thecommunication base station and inside the terminal by subtracting thepropagation delay time from the total delay.

Further, the information supply device can transmit the device peculiardelay information to a positioning terminal for carrying out positioningbased on the communication signal from the communication base station,by the device peculiar delay information transmitting means.

Here, the positioning terminal has a constituent element which isidentical to the terminal with respect to reception of the base stationtiming signal and the communication signal, and thus, a delay of thebase station timing signal inside the positioning terminal is in thesame range as the terminal. On the other hand, a delay of the basestation timing signal inside the communication base station is common inthe positioning terminal and the terminal. That is, the device peculiardelay information is also information indicating a delay inside thecommunication base station and inside the positioning terminal.

Thus, the positioning terminal can reduce an error in positioningcomputation in the case where the terminal carries out positioning basedon the communication signal from the communication base station.

As described above, according to the configuration of the first aspectof the invention, there can be provided a correction value of atransmission timing of a signal from a base station capable of reducingan error in positioning computation using a positioning terminal withouta need for a significant system change of the communication basestation.

According to a second aspect of the invention, the advantage can beattained by an information supply device communicable with acommunication base station, the information supply device comprising:base station position information storage means for storing base stationposition information indicating a position of the communication basestation; current position information receiving means for receivingcurrent position information generated based on satellite signals whichare signals from positioning satellites from a terminal via thecommunication base station; total delay information receiving means forreceiving total delay information from the terminal via thecommunication base station, the total delay information indicating atotal delay which is a timing difference between a base station timingsignal included in a communication signal from the communication basestation and a timing signal of the terminal corrected based on asatellite time which is a time of positioning satellites from theterminal via the communication base station; distance informationgenerating means for generating distance information indicating adistance between a current position of the terminal and a position ofthe communication base station based on the current position informationand the base station position information; propagation delay informationgenerating means for generating propagation delay information indicatinga propagation delay time required for the communication signal topropagate the distance; device peculiar delay information for generatingdevice peculiar delay information indicating a delay other than thepropagation delay time from among the total delay based on the totaldelay information and the propagation delay information; and devicepeculiar delay information transmitting means for transmitting thedevice peculiar delay information to a positioning terminal for carryingout positioning based on the communication signal from the communicationbase station, the positioning terminal having a configuration identicalto the terminal with respect to reception of the base station timingsignal and the communication signal.

According to the configuration of the second aspect of the invention, asin the configuration of the first aspect, it is possible to provide acorrection value of a transmission timing of a signal from acommunication base station capable of reducing an error in positioningcomputation using a positioning terminal without a need for significantsystem change of the communication base station.

According to a third aspect of the invention, it is preferable that theinformation supply device has: receiving condition information receivingmeans for receiving condition information indicating a receivingcondition of the satellite signals when the current position informationhas been generated from the terminal; and basic information selectingmeans for selecting the current position information and the total delayinformation for use in generating the distance information, thepropagation delay information, and the device peculiar delay informationfrom among the current position information and the total delayinformation received from a plurality of the terminals, based on thereceiving condition information in the structure of the second aspect ofthe invention.

There are various receiving conditions of the satellite signals when theterminal generates the current position information. For example, in thecase where a small number of the positioning satellites can be traced orin the case where signal strength of the satellite signals are weak andthe receiving condition is poor because of an indoor environment forexample, an error of the current position information is large. Theerror of the current position information is reflected on an error ofthe distance information which the information supply device generates.Further, the error of the distance information is reflected on thepropagation delay information and the device peculiar delay informationas well. That is, if the receiving condition is poor and the error ofthe current position information is large, precision of the devicepeculiar delay information is also degraded.

In this regard, the information supply device has the basic informationselecting means, and thus, can select the current position informationand the total delay information for use in generation of the distanceinformation, the propagation delay information, and the device peculiardelay information, from among the current position information and thetotal delay information received from a plurality of the terminals basedon the receiving condition information. Thus, the information supplydevice can select the current position information and the total delayinformation generated in the good receiving condition.

In this manner, the information supply device can generate the devicepeculiar delay information with high precision.

According to a fourth aspect of the invention, it is preferable that thecurrent position information receiving means, the total delayinformation receiving means, and the receiving condition informationmeans receives the current position information, the total delayinformation, and the receiving condition information respectively fromthe terminal at a predetermined time interval in the structure accordingto the third aspect of the invention.

As described previously, the device peculiar delay information indicatesa delay of the base station timing signal inside the information supplydevice and inside the terminal.

Here, for example, a drift of the information supply device changesdepending on a temperature, and is effected by a weather condition or atemperature change within a day as well. Further, parts such as cablesor filters configuring the information supply device are degraded withan elapse of time, and a delay of the base station timing signal causedby these parts changes. This situation also applies to the terminal aswell.

Therefore, it is desirable to update the device peculiar delayinformation.

In this regard, according to the configuration of the fourth aspect ofthe invention, the current position information receiving means, thetotal delay information receiving means, and the receiving conditioninformation receiving means, of the information supply device, arefeatured to receive the current position information, the total delayinformation, and the receiving condition information respectively fromthe terminal at a predetermined time interval, and thus the devicepeculiar delay information can be updated at the predetermined interval.

According to a fifth aspect of the invention, the advantage can beattained by a terminal communicable with a communication base station,the terminal comprising: current position information generating meansfor generating current position information indicating a currentposition based on satellite signals which are signals from positioningsatellites; satellite time information generating means for generatingsatellite time information indicating a satellite time which is a timeof the positioning satellites based on the satellite signals; standardtiming signal correcting means for correcting a standard timing signalbased on the satellite time information; total delay informationgenerating means for generating total delay information indicating atotal delay which is a timing difference between a base station timingsignal of the communication base station and the standard timing signal;and basic information transmitting means for transmitting basicinformation including the current position information and the totaldelay information to an information supply device for generating devicepeculiar delay information indicating a delay other than the propagationdelay time from among the total delay based on base station positioninformation indicating a position of the communication base station, thetotal delay information, and the current position information.

According to the configuration of the fifth aspect of the invention, theterminal has the basic information transmitting means, and thus, cantransmit basic information including the current position informationand the total delay information, the basic information forming a basisfor generating the device peculiar delay information, to the informationsupply device. Then, the information supply device can generate thedevice peculiar delay information based on the basic information andprovide the device peculiar delay information to a positioning terminalfor carrying out positioning based on the communication signal.

In this manner, it is possible to provide information that forms a basisfor generating a correction value of a transmission timing of a signalfrom a communication base station capable of reducing an error inpositioning computation using a positioning terminal without a need fora significant system change of the communication base station.

According to a sixth aspect of the invention, the advantage can beattained by a control method for controlling an information supplydevice comprising the steps of receiving current position informationgenerated based on satellite signals which are signals from positioningsatellites via the communication base station by means of an informationsupply device having base station position information storage means forstoring base station position information indicating a position of acommunication base station; receiving total delay information indicatinga total delay which is a timing difference between a base station timingsignal of the communication base station and a standard timing signal ofthe terminal corrected based on a satellite time which is a time of apositioning satellite from the terminal via the communication basestation by means of the information supply device; generating distanceinformation indicating a distance between a current position of theterminal and a position of the communication base station based on thecurrent position information and the base station position informationby means of the information supply device; generating propagation delayinformation indicating propagation delay time required for thecommunication signal to propagate the distance by means of theinformation supply device; and generating device peculiar delayinformation indicating a delay other than the propagation delay timefrom among the total delay based on the total delay information and thepropagation delay information by means of the information supply device.

According to the configuration of the sixth aspect of the invention, asin the configuration of the first aspect of the invention, it ispossible to provide a correction value of a transmission timing of asignal from a communication base station capable of reducing an error inpositioning computation using a positioning terminal without a need fora significant system change of the communication base station.

According to a seventh aspect of the invention, the advantage can beattained by a program for controlling an information supply deviceletting a computer execute the steps of: receiving current positioninformation generated based on satellite signals which are signals frompositioning satellites via the communication base station by means of aninformation supply device having base station position informationstorage means for storing base station position information indicating aposition of a communication base station; receiving total delayinformation indicating a total delay which is a timing differencebetween a base station timing signal of the communication base stationand a standard timing signal of the terminal corrected based on asatellite time which is a time of a positioning satellite from theterminal via the communication base station by means of the informationsupply device; generating distance information indicating a distancebetween a current position of the terminal and a position of thecommunication base station based on the current position information andthe base station position information by means of the information supplydevice; generating propagation delay information indicating propagationdelay time required for the communication signal to propagate thedistance by means of the information supply device; and generatingdevice peculiar delay information indicating a delay other than thepropagation delay time from among the total delay based on the totaldelay information and the propagation delay information by means of theinformation supply device.

According to a eighth aspect of the invention, the advantage can beattained by, a computer readable recording medium for storing a programfor controlling an information supply device for letting a computerexecute the steps of: receiving current position information generatedbased on satellite signals which are signals from positioning satellitesvia the communication base station by means of an information supplydevice having base station position information storage means forstoring base station position information indicating a position of acommunication base station; receiving total delay information indicatinga total delay which is a timing difference between a base station timingsignal of the communication base station and a standard timing signal ofthe terminal corrected based on a satellite time which is a time of apositioning satellite from the terminal via the communication basestation by means of the information supply device; generating distanceinformation indicating a distance between a current position of theterminal and a position of the communication base station based on thecurrent position information and the base station position informationby means of the information supply device; generating propagation delayinformation indicating propagation delay time required for thecommunication signal to propagate the distance by means of theinformation supply device; and generating device peculiar delayinformation indicating a delay other than the propagation delay timefrom among the total delay based on the total delay information and thepropagation delay information by means of the information supply device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic diagram showing a positioning system according toan embodiment of the invention;

FIG. 2 is a schematic diagram showing a primary hardware configurationof a base station;

FIG. 3 is a schematic diagram showing an example of a configuration of abase station communication apparatus;

FIG. 4 is a schematic diagram showing a primary hardware configurationof a terminal;

FIG. 5 is a schematic diagram showing a primary hardware configurationof a management server;

FIG. 6 is a schematic diagram showing a primary hardware configurationof a positioning terminal;

FIG. 7 is a schematic diagram showing a primary software configurationof a base station;

FIG. 8 is a schematic diagram showing a sending frame FR or the like;

FIG. 9 is a schematic diagram showing a primary software configurationof a terminal;

FIG. 10 is a schematic diagram showing a primary software configurationof a management server;

FIG. 11 is an illustrative diagram illustrating an example of a basestation positioning method;

FIG. 12 is a flow chart showing an example of operation of a positioningsystem; and

FIG. 13 is a schematic flow chart showing an example of operation of apositioning system.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, with reference to the drawings, the exemplary embodiment(s)of this invention will be described in detail.

The following embodiments are given various limitations that arepreferable technically because they are the exemplary specific examplesof the invention, however, the scope of the invention is not limited tothese aspects unless there is a particular description to limit theinvention in the following descriptions.

FIG. 1 is a schematic diagram showing a positioning system 10 accordingto an embodiment of the invention.

As shown in FIG. 1, the positioning system has a base station 20. Thisbase station 20 is an example of a communication base station. The basestation is, for example, a communication base station of a portablecellular phone network.

The base station 20 transmits a communication signal CS1. Thecommunication signal CS1 is provided as an example of a communicationsignal.

A plurality of the base station 20 is present. For example, basestations 20A, 20B, and 20C exist in their different positions from eachother. The base station 20A or the like transmits communication signalsCS1 a, CS1 b, and CS1 c. Hereinafter, it is assumed that the basestation 20 is generally referred to as the base station 20A or the like.

The positioning system 10 has a terminal 40 communicable with the basestation 20. This terminal 40 is provided as an example of a terminal.

A plurality of the terminal 40 is present. For example, terminals 40A,40B, and 40C exist. Hereinafter, it is assumed that the terminal 40 isreferred to as the terminals 40A or the like.

The positioning system 10 has a management server 60 (hereinafter,referred to as a server 60) communicable with the base station 20 andthe terminal 40 via a lease line network 55, for example. The server 60is an example of an information supply device.

Unlike the present embodiment, the communication network may be theInternet.

The positioning system 10 has a positioning terminal 80. The positioningterminal 80 can carry out positioning based on a communication signalCS1 from the base station 20. That is, the positioning terminal 80 isprovided as an example of a positioning terminal.

The base station 20, the terminal 40, and the positioning terminal 80can receive signals S1, S2, S3, and S4 from GPS satellites 12 a, 12 b,12 c, and 12 d, which are positioning satellites, for example. signalsS1, S2, S3 are examples of satellites signals.

The terminal 40 and the positioning terminal 80 are, for example, aportable cellular phone, a PHS (Personal Handy-phone System), a PDA(Personal Digital Assistance, etc.).

But The terminal 40 and the positioning terminal 80 are not limited tothe above.

Unlike the present embodiment, three or five or more GPS satellites 12 aor the like may be provided. In addition, unlike the present embodiment,four or more base stations 20 may be provided, and four or moreterminals 40 may be provided.

Primary Hardware Configuration of Base Station 20

FIG. 2 is a schematic diagram showing a primary hardware configurationof the base station 20.

As shown in FIG. 2, the base station 20 has a computer, and the computerhas a bus 22.

A CPU (Central Processing Unit) 23, a storage apparatus 24, and anexternal storage apparatus 25 or the like are connected to this bus 22.The storage apparatus 24 is a RAM (Random Access Memory) or a ROM (ReadOnly Memory) or the like, for example. The external storage apparatus 25is a HD (Hard Disk) for example.

In addition, an input apparatus 26 for inputting a variety ofinformation or the like and a base station GPS apparatus 27 areconnected to this bus 22. The base station GPS apparatus 27 is aconfiguration for the base station 20 to receive the signal S1 or thelike from the GSP satellite 12 a or the like.

In addition, a base station communication apparatus 28 is connected tothe bus 22. The base station communication apparatus 28 is aconfiguration for transmitting the communication signal CS1 forcommunicating with the terminal 40. The base station 20 transmits a basestation timing signal TS1 (refer to FIG. 8) together with thecommunication signal CS1. This base station timing signal TS1 is anexample of a base station timing signal.

FIG. 3 is a schematic diagram showing a configuration of a base stationcommunication apparatus 28.

As shown in FIG. 3, the base station communication apparatus 28includes: a timing signal generating apparatus 28 a for generating abase station timing signal TS1; a filter 28 b, and an amplifier 28 c orthe like. The base station communication apparatus 28 has a cable 28 dfor connecting the amplifier 28 c and an antenna 28 e with each other.

The timing signal generating apparatus 28 a has a quartz oscillator, forexample, for generating a signal which forms a base of the base stationtiming signal TS1. A standard frequency of this quartz oscillator isshifted depending on a temperature. Hereinafter, a shift of a frequencyof the quartz oscillator depending on a temperature is referred to as adrift. A signal transmission timing of the base station timing signalTS1 is changed (delayed) due to this drift.

In addition, with the base station timing TS1 generated by the timingsignal generating apparatus 28 a, a delay occurs in the filter 28 b, theamplifier 28 c, and the cable 28 d.

In addition, a display apparatus 29 for displaying a variety ofinformation or the like, a base station clock 30, and a base stationsecond communication apparatus 31 are connected to this bus 22.

Primary Hardware Configuration of Terminal 40

FIG. 4 is a schematic diagram showing a primary hardware configurationof the terminal 40.

As shown in FIG. 4, the terminal 40 has a computer, and the computer hasa bus 42.

A CPU 43, a storage apparatus 44, an input apparatus 45, a terminal GPSdevice 46, a terminal communication device 47, a display apparatus 48,and a terminal clock 49 are connected to this bus 42.

As described later, the terminal clock 49 can be maintained in a statein which there is no difference from a time of the GPS satellite 12 a orthe like (hereinafter, referred to as a GPS time).

Primary Hardware Configuration of Management Server 60

FIG. 5 is a schematic diagram showing a primary hardware configurationof the server 60.

As shown in FIG. 5, the server 60 has a computer, and the computer has abus 62.

A CPU 63, a storage apparatus 64, an external storage apparatus 65, aninput apparatus 66, a server communication apparatus 67, and a displayapparatus 68 are connected to this bus 62.

Primary Hardware Configuration of Positioning Terminal 80

FIG. 6 is a schematic diagram showing a primary hardware configurationof a positioning terminal 80.

As shown in FIG. 6, the primary hardware configuration of thepositioning terminal 80 is identical to that of the terminal 40described above.

This positioning terminal 80 has the same configuration as the terminal40 with respect to reception of a base station timing signal TS1 (referto FIGS. 8A and 8B) and a communication signal CS1 from the base station20. In addition, this positioning terminal also has the sameconfiguration as the terminal 40 with respect to reception of a signalS1 from the GPS satellite 12 a or the like.

Primary Software Configuration of Base Station 20

FIG. 7 is a schematic diagram showing a primary software configurationof the base station 20.

As shown in FIG. 7, the base station 20 has: a base station controlsection 100 for controlling each section; a base station GPS section 102which corresponds to the base station GPS apparatus 27 shown in FIG. 2;and a base station communication section 104 which corresponds to thebase station communication apparatus 28, or the like. This base stationcommunication section 104 is an example of signal transmitting means fortransmitting a base station timing signal TS1 and a communication signalCS1.

The base station 20 also has: a base station clock section 106 whichcorresponds to the base station clock 30 shown in FIG. 2; and a basestation second communication part 108 which corresponds to the basestation second communication apparatus 31, or the like.

The base station 20 further has: a base station first storage part 120for storing a variety of programs; and a base station second storagepart 150 for storing a variety of information.

As shown in FIG. 7, the base station 20 stores satellite orbitinformation 152 in the base station second storage part 150. Thesatellite orbit information 152 includes, for example, Almanac which isschematic orbit information of all the GPS satellites 12 a and the likeand Ephemeris which is precise orbit information of each of the GPSsatellites 12 a and the like. The satellite orbit information 152 isused to carry out positioning based on a signal S1 or the like from theGPS satellite 12 a or the like.

The base station control section 100 periodically receives a signal S1or the like from the GPS satellite 12 a or the like by means of the basestation GPS section 102 so as to sample Almanac and Ephemeris from thesignal S1 or the like. Almanac is updated by seven days, for example,Ephemeris is updated by four hours, for example, and they are maintainedin an always effective state.

As shown in FIG. 7, the base station 20 stores a base station positioninformation generating program 122 in the base station first storagepart 120. The base station position information generating program 122is a program for generating base station position information 154indicating a position of the base station 20 based on the signal S1 orthe like received by the base station control section 100 through thebase station GPS section 102.

Specifically, the base station control section 100 receives signals S1or the like from four or more GPS satellites 12 a or the like by meansof the base station GPS section 102. Then, the base station controlsection 100 computes a difference between a time at which each signal S1or the like has been transmitted and a time at which each signal S1 orthe like has been received; and obtains a distance (herein afterreferred as pseudo distance) between each of the GPS satellites 12 a orthe like and the base station 20 based on the fact that a propagationspeed of the signal S1 or the like is an light speed. Then, the basestation control section 100 computes a position on a satellite orbit, ofeach of the GPS satellites 12 a or the like at a current time by meansof Ephemeris included in the satellite orbit information 152. Then, thebase station control section 100 generates the base station positioninformation 154 indicating a position of the base station 20, forexample, by a latitude, a longitude, and an altitude, based on a pseudodistance of each of the GPS satellites 12 a or the like and the positionthe GPS satellites 12 a or the like on the satellite orbit.

The base station control section 100 stores the generated base stationposition information 154 in the base station second storage part 150.

As shown in FIG. 7, the base station 20 stores a sending framegenerating program 124 in the base station first storage part 120. Thesending frame generating program 124 is a program for the base stationcontrol section 110 to put sending time information 156 on acommunication signal CS1.

FIG. 8 is a schematic diagram showing a sending frame FR or the liketransmitted by the base station communication section 104.

As shown in FIG. 8, the sending frame FR is composed of subsidiaryframes SF1 to SF7, for example. Each subsidiary frame SF1 or the likeincludes information indicating sending times t1 to t7 of eachsubsidiary frame SF1 or the like. The sending time t1 or the like isclocked by means of a base station clock section 106.

The base station 20 continuously transmits a base station timing signalTS1 together with a communication signal CS1 or the like by means of thebase station communication section 104. The base station timing signalTS1 is an example of a base station timing signal. The base stationtiming signal TS1 is a pulse signal having an interval of one second,for example. The sending time t1 or the like and the base station timingsignal TS1 both are provided as information output from the base stationclock section 106, and thus, a difference between the sending time t1 orthe like and a GPS time is equal to a shift of a transmission timing ofthe base station timing signal TS1. Assuming that the base stationtiming signal TS1 is a pulse signal of an interval of one second, theshift of the transmission timing of the base station timing signal TS1used here denotes a time difference between a pulse interval of anactual base station timing signal ST1 and an interval of one secondmeasured by the GPS time. In the present specification, the shift of thetransmission timing of the base station timing signal TS1 is alsohandled as a delay.

As shown in FIG. 7, the base station 20 stores a basic informationdemanding program 126 in the base station first storage part 120. Thebasic information demanding program 126 is a program for requestingbasic information 262 described later (refer to FIG. 9) to the terminal40.

The base station 20 stores the basic information 262 received from theterminal 40 in the base station second storage part 150 as a part ofbase station side basic information 158. The base station side basicinformation 158 includes base station position information 154 as wellas the information included in the basic information 262 received fromthe terminal 40.

As shown in FIG. 7, the base station 20 stores a basic informationtransmitting program 128 in the base station first storage part 120. Thebasic information transmitting program 128 is a program for the basestation control section 100 to transmit the base station side basicinformation 158 to the server 60.

As shown in FIG. 7, the base station 20 stores a device peculiar delayinformation demanding program 130 in the base station first storage part120. The device peculiar delay information demanding program 130 is aprogram for requesting device peculiar delay information 372 (refer toFIG. 10) relating to the base station 20. Details of the device peculiardelay information 372 are described below. A base station 20A requeststhe device peculiar delay information 372 relating to the base station20A; a base station 20B requests the device peculiar delay information372 relating to the base station 20B; and a base station 20C requeststhe device peculiar delay information 372 relating to the base station20C. Thus, each base station 20A or the like requests the devicepeculiar delay information 372 on each base station 20A or the likeitself.

The base station control section 100 stores the device peculiar delayinformation 372 received from the server 60 in a base station secondstorage section 150 as the base station side device peculiar delayinformation 166.

As shown in FIG. 7, the base station 20 stores a base station sidedevice peculiar delay information supply program 132 in the base stationfirst storage part 120. The base station side device peculiar delayinformation supply program 132 is a program for the base station controlsection 100 to transmit a base station side device peculiar delayinformation 166 to a positioning terminal 80.

The base station control section 100 carries out transmission andreception of information by the above described basic informationdemanding program 126, basic information transmitting program 128,device peculiar delay information demanding program 130, and basestation side device peculiar delay information supply program 132 bymeans of a base station second communication part 108.

Thus, the base station 20 carries out transmission and reception ofinformation by the above described basic information demanding program126 or the like by means of the base station second communication part108, and thus, does not require a significant system change of a generalcommunication base station.

Primary Software Configuration of Terminal 40

FIG. 9 is a schematic diagram showing a primary software configurationof the terminal 40.

As shown in FIG. 9, the terminal 40 has: a terminal control section 200for controlling each section; a terminal GPS section 202 whichcorresponds to the terminal GPS device 46 shown in FIG. 4; a terminalcommunication section 204 which corresponds to the terminalcommunication device 47; and a terminal clock section 206 whichcorresponds to the terminal clock 49, or the like.

The terminal 40 further has a terminal first storage section 210 forstoring a variety of programs and a terminal second storage section 250for storing a variety of information.

As shown in FIG. 9, the terminal 40 stores terminal side satellite orbitinformation 252 in the terminal second storage section 250. The terminalside satellite orbit information 252 includes Almanac and Ephemeris, andis maintained in its effective state.

As shown in FIG. 9, the terminal 40 stores a current positioninformation generating program 212 in the terminal first storage section210. The current position information generating program 212 is aprogram for the terminal control section 200 to generate currentposition information 254 indicating a current position based on thesignal S1 or the like from the GPS satellite 12 a received by theterminal control section 200 by means of the terminal GPS section 202.This current position information 254 is an example of current positioninformation. In addition, the current position information generatingprogram 212 and terminal control section 200 are as a whole an exampleof current position information generating means.

The current position information 254 is an information indicating acurrent position of the terminal 40, for example, by a latitude, alongitude, and an altitude.

As shown in FIG. 9, the terminal 40 stores a GPS time informationgenerating program 214 in the terminal first storage section 210. TheGPS time information generating program 214 is provided as a program forthe terminal control section 200 to generate GPS time information 256indicating a GPS time based on the signal S1 or the like from the GPSsatellite 12 a or the like. This GPS time is an example of a satellitetime, and the GPS time information 256 is an example of satellite timeinformation. In addition, the GPS time information generating program214 and terminal control section 200 are as a whole an example ofsatellite time information generating means.

The terminal control section 200 computes a latitude, a longitude, andan altitude, for example, by means of positioning computation performedbased on the current position information generating program 212. Atthis time, this control section also computes a time error of a terminalclock section 206. Then, the terminal control section 200 computes a GPStime at the time of reception of the signal S1 or the like based on atime measured by the terminal clock section 206 and a time erroracquired by positioning.

The terminal control section 200 stores the generated GPS timeinformation 256 in the terminal second storage section 250.

Here, the terminal GPS device 46 (refer to FIG. 4) is composed of partssuch as an antenna, a cable, an amplifier, and a filter. After a signalS1 has been received by an antenna, a delay occurs inside the terminal40. Thus, the GPS time indicated in the GPS time information 256includes a difference from a true GPS time when the signal CS1 has beenreceived (hereinafter, referred to as a GPS time difference).

The terminals 40A, 40B, and 40C have the same configuration with respectto reception of the signal S1 or the like. Thus, the GPS time differencein terminals 40A, 40B, and 40C are values in the same range.

As shown in FIG. 9, the terminal 40 stores a receiving conditioninformation generating program 216 in the terminal first storage section210. The receiving condition information generating program 216 is aprogram for the terminal control section 200 to generate receivingcondition information 258 indicating a receiving condition of a signalS1 or the like used for generating the current position information 254.This receiving condition information 258 is an example of receivingcondition information.

The receiving condition information 258 is an information indicating allor part of PDOP (Position Dilution Of Precision), signal strength ofsignal S1 or the like, and the number of received GPS satellites, forexample.

The terminal control section 200 stores the generated receivingcondition information 258 in the terminal second storage section 250.

As shown in FIG. 9, the terminal 40 stores a standard timing signalcorrecting program 218 in the terminal first storage section 210. Thestandard timing signal correcting program 218 is a program for theterminal control section 200 to correct a standard timing signal TS2generated in the terminal clock section 206 (refer to FIG. 8( b)) basedon an interval of one seconds based on the GPS time indicated in the GPStime information 256, and then, maintain a pulse signal having aninterval of one second in GPS time. The standard timing signal TS2generated in the terminal clock section 206 is an example of a standardtiming signal.

As shown in FIG. 9, the terminal 40 stores the base station timingsignal receiving program 220 in the terminal first storage section 210.The base station timing signal receiving program 220 is a program forthe terminal control section 200 to receive the base station timingsignal TS1 from the base station 20 by means of the terminalcommunication section 204. That is, the base station timing signalreceiving program 220 and the terminal control section 200 are means forreceiving the base station timing signal.

As shown in FIG. 9, the terminal 40 stores a total delay informationgenerating program 222 in the terminal first storage section 210. Thetotal delay information generating program 222 is a program for theterminal control section 200 to generate total delay information 260indicating a total delay dt which is a timing difference between a basestation timing signal TS1 and a standard timing signal TS2. The totaldelay information 260 is an example of total delay information.

Specifically, the terminal control section 200, as shown in FIG. 8( b),measures a difference between a rise of the standard timing signal TS2and a rise of the base station timing signal TS1 by means of a basestation clock section 106, and computes a total delay dt. This totaldelay dt includes: a delay dt1 due to a drift in the base stationcommunication apparatus 28 (refer to FIG. 3); a cable delay and a devicedelay dt2 of a respective one of the base station 20 and the terminal40; and a propagation delay dt3 for propagation of the base stationtiming signal TS1 from the base station 20 to the terminal 40. Here, adelay obtained by totalizing the delay dt1 due to a drift and the delaydt2 inside the base station 20 and inside the terminal 40 such as acable delay or a device delay is referred to as a device peculiar delaydmt. The device peculiar delay dmt is obtained by subtracting thepropagation delay dt3 from the total delay dt. The device peculiar delaydmt is common in the case where the terminals 40A, 40B, and 40C receivea base station timing signal TS1 from the same base station 20A, forexample.

However, it is only the total delay dt that is computed by the terminal40.

The terminal control section 200 stores the generated total delayinformation 260 in the terminal second storage section 250.

Then, the terminal control section 200 stores the above describedcurrent position information 254, receiving condition information 258,and total delay information 260 in the terminal second storage section250 as constituent elements of basic information 262.

As shown in FIG. 9, the terminals 40 stores a basic informationtransmitting program 224 in the terminal first storage section 210. Thebasic information transmitting program 224 is provided as a program forthe terminal control section 200 to transmit the basic information 262to the base station 20.

The base station 20 having received the basic information 262 from theterminal 40 uses the basic information 262 as part of the base stationside basic information 158, as described above. In addition, the basestation 20 can transmit the base station side basic information 158 tothe server 60. That is, the terminal 40 can transmits the basicinformation 262 to the server 60 via the base station 20. That is, thebasic information transmitting program 224 and terminal control section200 are as a whole an example of basic information transmitting means.

Primary Software Configuration of Management Server 60

FIG. 10 is a schematic diagram showing a primary software configurationof a server 60.

As shown in FIG. 10, the server 60 has: a server control section 300 forcontrolling each section; and a server communication section 302 whichcorresponds to the server communication apparatus 67 shown in FIG. 5, orthe like.

The server 60 further has: a server first storage section 310 forstoring a variety of programs and a server second storage section 350for storing a variety of information.

The server 60 receives base station side basic information 158 (refer toFIG. 7) from the base station 20 by means of the server communicationsection 302. Then, this server stores the base station side basicinformation 158 as server side basic information 354 in a basicinformation database 352 of the server second storage section 350. Thebase station position information 154 shown in FIG. 7 corresponds to theserver side base station position information 356 shown in FIG. 10; theterminal current position information 160 corresponds to the server sideterminal current position information 358; the receiving conditioninformation 162 corresponds to the server side receiving conditioninformation 360; and the total delay information 164 corresponds to theserver side total delay information 362.

The above-described basic information database 352 is an example of basestation position information storage means.

In addition, as described above, the base station 20 retains the basicinformation 262 received from the terminal 40 as a constituent elementof the base station side basic information 158, and thus, it is possibleto say that the server communication section 302 receives the basicinformation 262 from the terminal 40 via the communication base station20. That is, the server communication section 302 is an example of basicinformation receiving means.

The server control section 300 is designed so as to receive the basestation side basic information 158 from the base station 20 at apredetermined time interval, for example, every one minute. This timeinterval of one minute is an example of a predetermined time interval.

Specifically, the server control section 300 requests the base stationside basic information 158 to the base station 20 at a time interval ofevery one minute. The base station having received a request from theserver 60 requests the latest basic information 262 (refer to FIG. 9) tothe terminal 40, receives the basic information 262, and defines thereceived basic information as new base station side basic information158 (refer to FIG. 7). Then, the base station 20 transmits the new basestation side basic information 158 to the server 60.

In this manner, the server 60 can receive the updated base station sidebasic information 158 at a time interval of every one minute.

As shown in FIG. 10, the server 60 stores a communicating base stationidentifying program 312 in the server first storage section 310. Thecommunicating base station identifying program 312 is a program for theserver control section 300 to specify a base station 20A, for example,with which the terminal 40 is in communication.

For example, the server control section 300 specifies the base station20A with which the terminal 40 is in communication, based on informationfor identifying the base station 20A, the information being loaded on acommunication signal CS1 a from the base station 20A. The informationfor identifying the base station 20A is an identification number of thebase station 20A, for example.

As shown in FIG. 10, the server 60 stores a basic information selectingprogram 314 in the server first storage section 310. The basicinformation selecting program 314 is a program for the server controlsection 300 to select the server side terminal current positioninformation 358 and server side total delay information 362 for use ingeneration of distance information 364, propagation delay information366, and device peculiar delay information 372 described later, fromamong the server side terminal current position information 358 andserver side total delay information 362 relating to a plurality ofterminals 40A or the like, based on the server side receiving conditioninformation 360. That is, the basic information selecting program 314and the server control section 300 are as a whole an example of basicinformation selecting means.

The server 60 stores server side receiving condition information 360 a,360 b, and 360 c relating to terminals 40A, 40B, and 40C respectively,for example, in the basic information database 352. In addition, theserver 60 stores server side terminal current position information 358a, 358 b, and 358 c and items of total delay information 362 a, 362 b,and 362 c for the terminal 40A or the like in the basic informationdatabase 352.

If the server side receiving condition information 360 indicates PDOP,in the case where the server side receiving condition information 360 aindicates the smallest PDOP, for example, the server control section 300selects the server side terminal current position information 358 a andthe total delay information 362 a for the terminal 40A.

As shown in FIG. 10, the server 60 stores a distance informationgenerating program 316 in the server first storage section 310. Thedistance information generating program 316 is a program for the servercontrol section 300 to generate distance information 364 indicating adistance L between a current position of the terminal 40A and a positionof the base station 20, based on the server side terminal currentposition information 358 a and the server side base station positioninformation 356. The distance information 364 is an example of distanceinformation. In addition, the distance information generating program316 and the server control section 300 are as a whole an example ofdistance information generating means.

Specifically, the server control section 300 generates the distanceinformation 364 by computing the distance L between a coordinate of thebase station 20 indicated in the server side base station positioninformation 356 and a coordinate of the terminal 40A indicated in theserver side terminal current position information 358 a.

The server control section 300 stores the generated distance information364 in the server second storage section 350.

In the case where the server side receiving condition information 360 aindicates the smallest PDOP, the server control section 300 selects theserver side terminal current position information 358 a for the terminal40A by means of the above described basic information selecting program314. Thus, a positioning error of the terminal 40A indicated in theserver side terminal current position information 358 a is smaller thana positioning error of the terminals 40B and 40C.

Thus, the server control section 300 can generates distance information364 whose error is the smallest.

As shown in FIG. 10, the server 60 stores a propagation delayinformation generating program 318 in the server first storage section310. The propagation delay information generating program 318 is aprogram for the server control section 300 to generate propagation delayinformation 366 indicating a propagation delay time dt3 required for acommunication signal CS1 to propagate the distance L indicated by thedistance information 364. That is, the propagation delay informationgenerating program 318 and the server control section 300 are as a wholean example of propagation delay information generating means.

Specifically, a speed of the communication signal CS1 to propagate is anlight speed, and thus, the server control section 300 computes thepropagation delay time dt3 by dividing the distance L by the lightspeed.

The server control section 300 stores the generated propagation delayinformation 366 in the server second storage section 350.

As described above, the server control section 300 can generate distanceinformation 364 whose error is the smallest, and thus, an error of thepropagation delay information 366 is also the smallest.

As shown in FIG. 10, the server 60 stores a device peculiar delayinformation generating program 320 in the server first storage section310. The device peculiar delay information generating program 320 is aprogram for the server control section 300 to generate device peculiardelay information 372 indicating a delay other than the propagationdelay time dt3, based on the server side total delay information 362 andthe propagation delay information 366. This device peculiar delayinformation 372 is provided as an example of device peculiar delayinformation. In addition, the device peculiar delay informationgenerating program 320 and the server control section 300 are as a wholean example of device peculiar delay information generating means.

Specifically, the server control section 300 computes a device peculiardelay dmt by subtracting a propagation delay time dt3 from a total delaydt (refer to FIG. 8( b)).

The server control section 300 stores the generated device peculiardelay information 372 in a device peculiar delay information database370 of the server second storage section 350.

The server control section 300 generates device peculiar delayinformation 372 a, 372 b, and 372 c relating to base stations 20A, 20B,and 20C, respectively. The constituent elements relating to transmissionof a base station timing signal TS1 inside the base stations 20A, 20B,and 20C are not always identical to each other, and thus, delay times ofthe base station timing signal TS1 inside the base stations 20A, 20B,and 20C are not always equal to one another. Therefore, the devicepeculiar delays dmta, dmtb, and dmtc indicated in device peculiar delayinformation 372 a, 372 b, and 372 c relating to the base stations 20A,20B, and 20C are not always equal to each other.

In contrast, for example, in terminals 40A, 40B, and 40C, theconstituent elements relating to reception of the base station timingsignal TS1 are identical to each other, and thus, the delay times of thebase station timing signal TS1 inside the terminals 40A, 40B, and 40Care equal to each other. In addition, an only difference in terminals40A, 40B, and 40C is a propagation delay time dt3 (refer to FIG. 8( b)).Thus, as long as the base station 20 is common, for example, a basestation 20A, the device peculiar delay dmt computed by subtracting thepropagation delay time dt3 from the total delay dt is equal with respectto the terminals 40A, 40B, and 40C.

As described above, the base station 20 can receive the above devicepeculiar delay information 372 from the server 60 and store base stationside device peculiar delay information 166 (refer to FIG. 7) in a basestation second storage part 150.

Then, a positioning terminal 80 can receive the base station side devicepeculiar delay information 166 from the base station 20 and carry outpositioning (hereinafter, referred to as base station positioning) basedon a communication signal CS1 a or the like from a plurality of basestations 20A or the like. In the case where it is judged thatcommunication with the base station 20B has been switched tocommunication with the base station 20A (in the case where it is judgedthat handover has occurred) or in the case where power has been suppliedfor startup, the positioning terminal 80 is designed to acquire the basestation side device peculiar delay information 166 (refer to FIG. 7)from the base station 20A.

FIG. 11 is a illustrative diagram showing an example of a base stationpositioning method.

FIG. 11( a) is a diagram showing a position of each base station 20A orthe like. The position of each base station 20A or the like is alreadyknown.

FIG. 11( b)d is a diagram showing a propagation time tb01 or the like ofa communication signal CS1 a or the like from each base station 20A orthe like. The propagation time tb01 or the like is an unknown quantity.

FIG. 11( c) is a diagram showing a sending time t1 or the like of eachcommunication signal CS1 a or the like. The sending time t1 or the likeis already known. Here, t1, t2, and t3 are not always identical to eachother.

FIG. 11( d) is a diagram showing a device peculiar delay dmta or thelike which is a total of a delay inside the base station 20A or the likeand a delay inside a terminal. The device peculiar delay dmta or thelike is already known.

FIG. 11( e) is a diagram showing a propagation speed of a communicationsignal CS1 a or the like. The communication signal CS1 a or the like isputted on a radio wave, and thus, its propagation speed is an lightspeed C.

FIG. 11( f) is a diagram showing a time difference td01 or the likebetween a sending time t1 of the communication signal CS1 a or the likeand a time at which the positioning terminal 80 has received thecommunication signal CS1 a or the like. As shown in FIG. 11( g), a timeat which the positioning terminal 80 has received the communicationsignal CS1 a or the like is defined as t0.

A position (X, Y, Z) of the positioning terminal 80 shown in FIG. 11( h)is an unknown quantity.

On the presumption of the foregoing description, a description will begiven with respect to formulas (1) to (9) shown in FIGS. 11( i) to11(k).

First, a distance between each base station 20A or the like and thepositioning terminal 80 is equal to a value obtained by multiplying apropagation time of a communication signal CS1 a or the like and a speedof a radio wave (light speed C) by each other, and thus, formulas (1) to(3) shown in FIG. 11( i) are established.

Next, a reception time of a communication signal CS1 a or the like is atime at which a propagation time tb01 or the like and a device peculiardelay dtma or the like has elapsed from a sending time t1 or the like,and thus, formulas (4) to (6) shown in FIG. 11( j) are established.

Further, with respect to the time difference td01 or the like shown inFIG. 11( f), formulas (7) to (9) shown in FIG. 11( k) are establishedbased on a sending time t1 or the like shown in FIG. 11( c), thepropagation time tb01 shown in FIG. 11( b), and a time t0 shown in FIG.11( g).

In the formulas, there are six unknown quantities X, Y, and Z indicatingpositions of the positioning terminal 80 and the propagation times tb01,tb02, and tb03, and thus, all of the unknown quantities can be computedby solving simultaneous equations (1), (2), (3), (7), (8), and (9).

The above base station positioning presumes that the positioningterminal 80 is communicable with the base station 20A or the like, andthus, this terminal is positioned in the communication coverage of thebase station 20A or the like. Thus, in the case where the positioningterminal 80 is positioned in a less irregular region and an altitudecomponent Z1 or the like of the position of the base station 20A or thelike (refer to FIG. 11( a)) is substantially equal to one another, forexample, the above described base station positioning can be carried outwhile an average value of the altitude components Z1, Z2, and Z3 isdefined as an altitude component Z of the position of the positioningterminal 80.

In addition, the positioning terminal 80 can carry out positioning(referred to as hybrid positioning) based on both of the communicationsignal CS1 a or the like and the signal S1 or the like from the GPSsatellite 12 a or the like.

The positioning terminal 80 carries out hybrid positioning whilesubstituting the GPS satellite 12 a or the like by one or two basestations 20 in the base station positioning computation method describedabove with respect to FIG. 11.

In general, positioning using artificial satellites, positioning mobilecommunication information, or a positioning method using two or moresensors such as an acceleration sensor using gyroscope and a vehiclespeed pulse sensor is referred to as hybrid positioning. However, in thepresent embodiment, positioning carried out by using a combination ofinformation on the base station 20A or the like and information on theGPS satellite 12 a or the like is referred to as hybrid positioning.

In addition, the positioning terminal 80 carries out positioning basedonly on a signal S1 or the like (hereinafter, referred to as satellitepositioning) in the case where it can receive the signal S1 or the likefrom three or more GPS satellites 12 a or the like.

In general, positioning precision of positioning based on the signal S1or the like from the GPS satellites 12 a or the like is higher than thatof positioning based on the communication signal CS1. For example, inthe case of satellite positioning, a positioning error ranges from 0 to20 meters. On the other hand, in the case of base station positioning,the positioning error ranges from 5 to 400 meters.

In this regard, the positioning terminal 80 can carry out positioning byusing only the signal S1 or the like or both of the signal S1 or thelike and the communication signal CS1 as long as it can receive thesignal S1 or the like from the GPS satellites 12 a or the like.

Thus, the positioning terminal 80 can carry out positioning in thehighest positioning precision in accordance with the number of GPSsatellites 12 a or the like which are in the sky and observable.

In contrast, for example, in an environment in which three or more GPSsatellites 12 a or the like cannot be observed, such as an indoorenvironment, hybrid positioning or base station positioning can becarried out by using a communication signal CS1 which can be receivedeven in the indoor environment.

The positioning system 10 is configured as described above.

As has been described above, the base station 20 can transmit the basestation timing signal TS1 and the communication signal CS1 generated bythe base station 20.

It is general that a communication base station transmits acommunication signal including a timing signal, and thus, thecommunication base station does not need a significant system change ofa general communication base station.

In addition, the terminal 40 can generate total delay information 260. Atotal delay dt is obtained as a timing difference between a base stationtiming signal TS1 and a standard timing signal TS2 corrected based on aGPS time. This total delay dt includes: a delay due to a drift when thebase station timing signal ST1 is generated in the base station 20; anda delay in the base station 20 from generation to transmission of thebase station timing signal TS1 in the base station 20.

In addition, the total delay dt includes a propagation delay time dt3required for the base station timing signal TS1 to arrive from the basestation 20 to the terminal 40.

Further, the total delay dt includes: a delay inside the terminal 40caused by the base station timing signal TS1 passing through a cable, afilter or the like after the signal has arrived at an antenna of theterminal 40.

Furthermore, the total delay dt includes a delay of the standard timingsignal TS2 itself as well. Although the standard timing signal TS2 iscorrected by the GPS time, the signal S1 or the like itself from the GPSsatellite 12 a or the like delays inside the terminal 40. As a result,with the standard timing signal ST2 as well, a delay occurs as comparedwith a timing of a true GPS time.

As described above, the total delay dt includes all the delays, i.e., adelay inside the base station 20, a propagation delay dt3 between thebase station 20 and the terminal 40 and a delay inside the terminal 40.In computation of the total delay dt, the terminal 40 does not need tocompute individual delays such as a delay caused by a drift or a cableinside the base station 20, for example, and does not need to computeindividual delays inside the terminal 40. This implies that an effect ofan error in individual delay computations inside the base station 20 andinside the terminal 40 and an effect of an error in propagation delaycomputation can be eliminated. That is, the total delay dt eliminates aneffect of an error in delay computation due to the individual causesdescribed above while including all of the delays inside the basestation 20, inside the terminal 40, and between the base station 20 andthe terminal 40.

On the other hand, the server 60 can receive base station side basicinformation 158 (refer to FIG. 7) from the base station 20.

In addition, the server 60 can generate distance information 364 (referto FIG. 10).

In addition, the server 60 can generate propagation delay information366.

Further, the server 60 can generate device peculiar delay information372.

The above described device peculiar delay information 372 is a delayother than the propagation delay dt3, and thus, is provided asinformation indicating delays inside the base station 20 and inside theterminal 40. As described above, the total delay dt is computed whileeliminating individual computation errors inside the base station 20 andthe terminal 40. In addition, the communication signal CS1 propagates atan light speed so that the server 60 can compute the propagation delaytime dt3 precisely.

As described above, the total delay dt eliminates an effect of a delaycomputation error due to the individual causes described above whileincluding all of the delays inside the base station 20, inside theterminal 40, and between the base station 20 and the terminal 40.

In addition, the server 60 can compute the propagation delay time dt3precisely. Thus, this server 60 can generate device peculiar delayinformation 372 while eliminating an effect of a delay computation errordue to the individual causes inside the base station 20 and inside theterminal 40 by subtracting the propagation delay time dt3 from the totaldelay dt.

Further, the server 60 can transmit the device peculiar delayinformation 372 via the base station 20 to the positioning terminal 80for carrying out positioning based on the communication signal CS1 fromthe base station 20.

Here, the positioning terminal 80 has the same constituent elements asthe terminal 40 with respect to reception of the communication signalCS1, and thus, a delay of the base station timing signal TS1 inside thepositioning terminal 80 is in the same range as that of the terminal 40.On the other hand, a delay of the base station timing signal TS1 insidethe base station 20 is common in the positioning terminal 80 and theterminal 40. That is, the device peculiar delay information 372 is alsoprovided as information indicating delays inside the base station 20 andinside the positioning terminal 80.

Thus, the positioning terminal 80 can reduce an error of positioningcomputation in the case where the positioning terminal 80 carries outpositioning based on the communication signal CS1 a or the like from theplurality of base stations 20 a by using the device peculiar delayinformation 372.

As described above, according to the positioning system 10, it ispossible to provide a correction value of a transmission timing of asignal from a communication base station capable of reducing an error inpositioning computation using a positioning terminal without a need fora significant system change of the communication base station.

In addition, there are a variety of receiving conditions of a GPS signalS1 or the like when the terminal 40 generates current positioninformation 254 (refer to FIG. 9). For example, in the case where asmall number of the GPS satellites 12 a or the like can be traced or inthe case where signal strength of the GPS signal S1 or the like is weakand the receiving condition is poor in an indoor environment, an errorof the current position information 254 is large. The error of thecurrent position information 254 is reflected on an error of thedistance information 364 (refer to FIG. 10) generated by the sever 60.Further, this error is reflected on the propagation delay information366 and the device peculiar delay information 372 as well. That is, ifthe receiving condition is poor and the error of the current positioninformation 254 is large, precision of the device peculiar delayinformation 372 is also degraded.

In this regard, the server 60 can select information for use ingeneration of the distance information 364, propagation delayinformation 366, and device peculiar delay information 372 from amongthe server side terminal current position information 358 and serverside total delay information 362 relating to a plurality of terminals 40based on the server side receiving condition information 360 (refer toFIG. 10). Thus, the server 60 can select the server side terminalcurrent position information 358 and server side total delay information362 generated in a good receiving condition.

In this manner, the server 60 can generate device peculiar delayinformation 372 with high precision. As a result, the positioningterminal 80 can improve the positioning precision of base stationpositioning and hybrid positioning carried out by using the base stationside device peculiar delay information 166 (refer to FIG. 7).

As described above, the device peculiar delay information 372 indicatesa delay of the base station timing signal TS1 inside the server 60 andinside the terminal 40.

Here, for example, a drift of the server 60 changes depending on atemperature, and is subjected to a weather condition or a temperaturechange within a day. Further, parts such as cables or filtersconfiguring the server 60 are degraded with an elapse of time, and adelay of the base station timing signal TS1 is changed by these partschanges. This situation also applies to the terminal 40.

Therefore, it is desirable that the device peculiar delay information372 be updated.

In this regard, the server 60 is featured to receive the updated basestation side basic information 158 from the base station 20 atpredetermined time intervals, for example, every one minute, so that thedevice peculiar delay information 372 can be updated at thepredetermined time intervals.

The description of the configuration of the positioning system 10according to the present embodiment has now been completed. Hereinafter,an example of an operation of the system will be described primarilywith reference to FIGS. 12 and 13.

FIGS. 12 and 13 are schematic flow charts each showing an example of anoperation of the positioning system 10 according to the presentembodiment.

First, the terminal 40 receives a request of basic information 262(refer to FIG. 9) from the base station 20 (step ST1 of FIG. 12).

Next, the terminal 40 receives a signal S1 or the like from GPSsatellites 12 a or the like, and generates current position information254, GPS time information 256, and receiving condition information 258(step ST2).

Then, the terminal 40 corrects a standard timing signal TS2 (refer toFIG. 8( b)) based on the GPS time information 256 (step ST3).

Then, the terminal 40 receives a base station timing signal TS1 (stepST4).

Then, the terminal 40 generates total delay information 260 (refer toFIG. 9) indicating a timing difference between the base station timingsignal TS1 and the standard timing signal TS2 (step ST5).

Then, the terminal 40 generates the basic information 262 includingcurrent position information 254, receiving condition information 258,and total delay information 260 with respect to the base station 20(step ST6).

Then, the base station 20 receives basic information 262 from theterminal 40 (step ST7 of FIG. 13).

Then, the base station 20 transmits base station side basic information158 (refer to FIG. 7) to the server 60 (step ST8).

Then, the server 60 receives the base station side basic information 158from the base station 20 (step ST9). This step ST9 is an example of thestep of receiving current position information and an example of thestep of receiving total delay information.

Then, the server 60 selects server side terminal current positioninformation 358 and server side total delay information 362 whichcorrespond to the terminal 40 which is the best in receiving conditionshown in the server side receiving condition information 360 (refer toFIG. 10) (step ST10).

Then, the server 60 generates distance information 364 (refer to FIG.10) indicating a distance L between a position of the terminal 40indicated in the server side terminal current position information 358and a position of the base station 20 indicated in the server side basestation position information 356 (step ST11). This step ST11 is anexample of the step of generating distance information.

Then, the server 60 generates propagation delay information 366indicating a propagation delay time dt3 by dividing the distance Lindicated in the distance information 364 by an light speed (step ST12).This step ST12 is an example of the step of generating propagation delayinformation.

Then, the server 60 subtracts the propagation delay time dt3 from atotal delay dt indicated in the server side total delay information 362,and generates device peculiar delay information 372 indicating a devicepeculiar delay dmt (refer to FIG. 8B (step ST13)). This step ST13 is anexample of the step of generating device peculiar delay information.

The server 60 can supply the thus generated device peculiar delayinformation 372 to the positioning terminal 80 via the base station 20.

As described above, in the positioning system 10, the server 60 cangenerate the device peculiar delay information 372 indicating a total ofa delay inside the base station 20 and a delay inside the terminal 40,and supply the generated information to the positioning terminal 80 viathe base station 20.

Then, the positioning terminal 80 carries out positioning based on thecommunication signal C1 sent from the base station 20 established inasynchronous communication. At this time, this positioning terminal 80uses the device peculiar delay information 372 acquired from the server60. In this manner, the precision of positioning computation of thepositioning terminal 80 can be improved.

As has been described above, according to the positioning system 10, itis possible to provide a correction value of a transmission timing of asignal from a communication base station capable of reducing an error ofpositioning computation using the positioning terminal without a needfor a significant system change of the communication base station.

Program and Computer Readable Recording Medium or the Like

An information supply device control program can be provided, theprogram causing a computer to execute the step of receiving currentposition information; the step of receiving total delay information; thestep of generating distance information; the step of generatingpropagation delay information; and the step of generating devicepeculiar delay information or the like, included in the above describedexample of operation.

In addition, a computer readable recording medium or the like can beprovided, the medium having recorded therein such an information supplydevice control program or the like.

A program storage medium to be used for installing the control programor the like of the information supply device and making it so as to beexecuted by the computer can be realized, for example, not only by apackage media such as a flexible disk such as a floppy (registeredtrademark) and a CD-ROM (Compact Disc Read Only Memory), a CD-R (CompactDisc-Recordable), a CD-RW (Compact Disc-Rewritable), and a DVD (DigitalVersatile Disc) or the like but also by a semiconductor memory, amagnetic disk or a magnetic optical disk for temporally or permanentlystoring the program therein.

The invention is not limited to the above-described respectiveembodiments. Further, the above-described respective embodiments may becombined with each other.

What is claimed is:
 1. An information supply method implemented by aninformation supply device, the method comprising: receiving a positionof each of a plurality of terminals via a first base station, theposition of each of the plurality of terminals being measuredrespectively by each of the plurality of terminals; receiving totaldelay information via the first base station, the total delayinformation being calculated by each of the plurality of terminals bymeasuring a timing difference between a standard timing signal that iscorrected in time based on a satellite signal and a base station timingsignal received from the first base station; receiving information abouta receiving condition of the satellite signal measured by each of theplurality of terminals via the first base station; selecting oneterminal from the plurality of terminals based on the receivingcondition of the satellite signals; calculating a propagation delay timebetween the one terminal and the first base station based on theposition of the one terminal received from the one terminal and aposition of the first base station; calculating a device peculiar delaytime based on the total delay information received from the one terminaland the propagation delay time, the device peculiar delay time occurringinside the first base station and the one terminal during communicationbetween the first base station and the one terminal; and supplying thedevice peculiar delay time.
 2. The information supply method accordingto claim 1, further comprising instructing the first base station totransmit a signal that requests measurement of latest information to aterminal among the plurality of terminals that is positioned in acommunication area of the first base station at predetermined timeintervals.